There is a frequent need in the case of electronic circuits for square wave signals, whose amplitude is higher than the value of a supply voltage of the electronic circuit.
Such a square wave signal can be generated in that in addition to a first supply voltage source, e.g. with an output voltage of 5V, a second voltage source is provided, e.g. with an output voltage of 10V. For generating the square wave signal, which alternates between a ground or earth voltage and 10V, a series resistor and a transistor are looped or coupled in series between the second voltage source and the ground voltage, being controlled by a microprocessor supplied with 5V with a 5V amplitude square wave signal. The output voltage is applied at a connection point between the series resistor and the transistor. If the transistor blocks or switched off, the output voltage is 10V, less the voltage decreasing at the series resistor. If the transistor is switched on, the output voltage is the transistor forward voltage, i.e., approximately 0V. However, due to the series resistor the higher output voltage value is highly load-dependent, because a load current causes a corresponding voltage drop at the series resistor. To reduce this load dependence, the series resistor should have a relatively low resistance. However, when the transistor is switched on, this gives rise to a high current, which flows across the transistor to earth in unused form. It is also necessary to have a second voltage source, so that the circuitry costs, space requirements and manufacturing costs of the circuit arrangement increase.
The technical problem of the invention is the provision of a circuit arrangement and a method for generating a square wave signal of the aforementioned type, which provide an output signal with lower load dependence and which can be inexpensively implemented with limited space requirements.